This is a poetic passage, full of wordplay, hence difficult to translate. A primary meaning of 涯 yá is "horizon," which is intriguing. To us, the horizon is something we constantly approach but never reach. I'm not sure it would have the same connotation to the ancient Chinese, however, not having circumnavigated the earth. And since the horizon is both there and not there, something we can see but not touch, saying that life has a horizon but knowledge has none is not as clear to me as I would like. Therefore I opt for a different translation: "shore." I believe the contrast is between a lake or a river (which has shores) and the ocean (which has none, or at least no far shore). If you tried to fill the ocean from a lake or a river, you would 'run out.'